Engine waste gas aftertreatment system

Abstract

The invention discloses an engine waste gas aftertreatment system, being used for purifying waste gas discharged from an exhaust pipe of the engine. The engine waste gas aftertreatment system comprises a catalytic converter, wherein the catalytic converter is connected with the exhaust pipe of the engine by virtue of a turbocharger, the turbocharger is connected with an air inlet pipe of the engine by virtue of an air inlet intercooler, the catalytic converter contains a catalyst which is used for an assisting reaction; when the engine is normally operated, an exhaust switching valve controls high temperature waste gas to enter into the catalytic converter, thus the high temperature waste gas enters into the air after being purified; and when the engine is in a reverse towing working condition, and the exhaust switching valve controls low temperature exhausted gas to enter into the engine to be circulated from a return line or is directly discharged into the air from a bypass pipeline, thus temperature of an aftertreatment device is not influenced by the low temperature exhausted gas. By adopting the engine waste gas aftertreatment system disclosed by the invention, the pipeline of the aftertreatment device is improved, the influence of exhaust to the temperature of the aftertreatment device is reduced, thus the aftertreatment device maintains high-efficiency purification exhaust when the engine is converted into the normal operation from the 'reverse towing' working condition, and hidden troubles that environment is polluted caused by the uncompleted waste gas purification can be effectively eliminated.

Description

technical field [0001] The invention relates to the field of engine manufacturing, in particular to an engine exhaust gas aftertreatment system. Background technique [0002] In order to meet the emission standards, the engine must be equipped with a set of exhaust after-treatment devices to purify the nitrogen oxides (NO X ), soot particles (PM), carbon monoxide (CO) and hydrocarbons (HC), etc. Usually aftertreatment requires a catalyst to assist the reaction, and its normal catalytic temperature is required to be above 200-250°C, and within a certain range, the higher the exhaust temperature, the higher the catalytic converter efficiency. [0003] In the prior art solution, the combustion exhaust gas of the engine flows through the turbocharger and directly enters the post-processing device, and then is purified by the post-processing technology and introduced into the muffler, and finally discharged into the atmosphere. In this way, under some special working conditions...

AI Technical Summary

Problems solved by technology

If the unburned low-temperature cooling air directly enters the post-processing device when the engine is "backwards", the temperature of the post-processing device will drop sharply and be lower than the normal catalytic temperature of the catalyst. , the post-treatment reaction is not complete, the purification of combustion exhaust gas is not complete, and the exhaust gas will pollute the environment after being discharged into the atmosphere

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